Going to get a pellet gun, if and when it loses power, will there be anyway to fix it?

I've owned two before, one that needed to be pumped and a break barrel. After some time they lost their power. The pump one wouldn't even penetrate a pop can using a bb. I never mistreated them like not took care of em. But when I get this new one I want to know if there's any way to prevent a loss of power and how to fix it if it happens. And it'll be a big break barrel pellet gun